Provided is a catalyst for methacrylic acid production, which has high methacrylic acid yield. A method for producing a catalyst for methacrylic acid production, which comprises: (1) a step for preparing a catalyst starting material liquid A that contains Mo, P and V; (2) a step for preparing a catalyst starting material liquid B that contains a cationic starting material; and (3) a step for preparing a liquid that contains a heteropolyacid having a Keggin-type structure or a salt of the heteropolyacid by adding one of the catalyst starting material liquid A and the catalyst starting material liquid B to the other and mixing together. In the step (3), formulae (i) and (ii) are satisfied.
3.0 ≤ T/(3√V) ≤ 13.0 (i)
0.01 ≤ u1 ≤ 1.0 (ii)
(In formulae (i) and (ii), V represents the volume [m3] of the catalyst starting material liquid A; T represents the number of addition ports through which the other liquid is added; u1 represents the volumetric flow rate [L/minute] of the other liquid added; and u1 represents the average in cases where T is 2 or more.)